Audi Cabriolet bucking on gear change

Does anyone have a view on this issue? My Audi Cab (1998 1.8) is hard to start. When it starts, it splutters in to life and then settles down. When driving, there is a noticeable loss of power and then over compensation in acceleration making the ride jurkey (especially when you change between first and second gear). When reversing, the revs can drop off and the car stalls. Its been in the garage, so far they have replaced the fuel injectors (for a refurbished set) and the Mass Air Flow Meter. Annoyingly, before I started down this route starting it was fine, the car ran smoother, however, petrol intake was rich, fuel burned quickly and there was a slight misfire ever so often.

I am also wondering if it could be the refurbished fuel injectors, as things got worse once these were in. The garage thought it could just be that it exposes another issue. Thing is, now the MAF has been replaced and they have fiddled with the timing, its even worse i.e now have the bucking acceleration on gear change and emissions are very smelly

Wish I just stuck with the initial issue which was a very small misfire when idle. everything else was working fine at that point